## 9.22. lookfor: Which File Has That Word?

The following simple shell script, lookfor, uses find to look for all files in the specified directory hierarchy that have been modified within a certain time, and it passes the resulting names to grep to scan for a particular pattern. For example, the command:

>     % lookfor /work -7 tamale enchilada

would search through the entire /work filesystem and print the names of all files modified within the past week that contain the words "tamale" or "enchilada." (For example, if this article is stored in /work, lookfor should find it.)

The arguments to the script are the pathname of a directory hierarchy to search in (`$1`), a time (`$2`), and one or more text patterns (the other arguments). This simple but slow version will search for an (almost) unlimited number of words:

>     #!/bin/sh
>     temp=/tmp/lookfor$$
>     trap 'rm -f $temp; exit' 0 1 2 15
>     find $1 -mtime $2 -print > $temp
>     shift; shift
>     for word
>     do grep -i "$word" `cat $temp` /dev/null
>     done

That version runs grep once to search for each word. The -i option makes the search find either upper- or lowercase letters. Using /dev/null makes sure that grep will print the filename. Watch out, though: the list of filenames may get too long.

The next version is more limited but faster. It builds a regular expression for egrep that finds all the words in one pass through the files. If you use too many words, egrep will say `Regular` `expression` `too` `long`. Also, your egrep may not have a -i option; you can just omit it. This version also uses xargs; though xargs has its problems.

>     #!/bin/sh
>     where="$1"
>     when="$2"
>     shift; shift
>     # Build egrep expression like (word1|word2|...) in $expr
>     for word
>     do
>         case "$expr" in
>         "") expr="($word" ;;
>         *) expr="$expr|$word" ;;
>         esac
>     done
>     expr="$expr)"

>     find $where -mtime $when -print | xargs egrep -i "$expr" /dev/null

--JP and TOR

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